I want to write a unit-test for some code which generates a powershell script and then check that the script has valid syntax.
What's a good way to do this without actually executing the script?
A .NET code solution is ideal, but a command line solution that I could use by launching an external process would be good enough.
I stumbled onto Get-Command -syntax 'script.ps1' and found it concise and useful.
ETA from the comment below: This gives a detailed syntax error report, if any; otherwise it shows the calling syntax (parameter list) of the script.
You could run your code through the Parser and observe if it raises any errors:
# Empty collection for errors
$Errors = @()
# Define input script
$inputScript = 'Do-Something -Param 1,2,3,'
[void][System.Management.Automation.Language.Parser]::ParseInput($inputScript,[ref]$null,[ref]$Errors)
if($Errors.Count -gt 0){
Write-Warning 'Errors found'
}
This could easily be turned into a simple function:
function Test-Syntax
{
[CmdletBinding(DefaultParameterSetName='File')]
param(
[Parameter(Mandatory=$true, ParameterSetName='File', Position = 0)]
[string]$Path,
[Parameter(Mandatory=$true, ParameterSetName='String', Position = 0)]
[string]$Code
)
$Errors = @()
if($PSCmdlet.ParameterSetName -eq 'String'){
[void][System.Management.Automation.Language.Parser]::ParseInput($Code,[ref]$null,[ref]$Errors)
} else {
[void][System.Management.Automation.Language.Parser]::ParseFile($Path,[ref]$null,[ref]$Errors)
}
return [bool]($Errors.Count -lt 1)
}
Then use like:
if(Test-Syntax C:\path\to\script.ps1){
Write-Host 'Script looks good!'
}
-path option? For me only Test-Syntax -path C:\path\to\script.ps1 seems to work, not Test-Syntax C:\path\to\script.ps1PS Script Analyzer is a good place to start at static analysis of your code.
PSScriptAnalyzer provides script analysis and checks for potential code defects in the scripts by applying a group of built-in or customized rules on the scripts being analyzed.
It also integrates with Visual Studio Code.
There are a number of strategies for mocking PowerShell as part of unit tests, and also have a look at Pester.
The Scripting Guy's Unit Testing PowerShell Code With Pester
PowerShellMagazine's Get Started With Pester (PowerShell unit testing framework)